Continuous method for producing pre-insulated piping

ABSTRACT

A method for the continuous production of pre-insulated piping having an inner metal carrier pipe having an interior surface and an exterior surface and an envelope of foamed insulation surrounding the inner metal carrier pipe exterior surface. A molding apparatus is provided for forming an annulus about a pipe to be insulated into which foam can be injected. The pipe is continuously moved through the apparatus with foaming material being injected into the annulus where it is molded and cured to form a foam insulated pipe. The molding apparatus is a roller-drum having a cylindrical length and a plurality of individual rollers arranged in a series of linearly staggered, circular arrays which define the annulus where the foaming material is cured.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from a provisional application, Ser.No. 62/369,941, filed Aug. 2, 2016, with the same title and by the sameinventor.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates generally to fully bonded foampre-insulated piping systems and, more specifically, to a method andapparatus for the continuous production of such piping systems.

Description of the Prior Art

Insulated pipelines are needed in a variety of situations. For example,distributed HVAC (heating, ventilation, and air conditioning)applications utilize chilled water for cooling and steam and hot waterfor heating. The chiller and boiler are typically contained in a centrallocation and the chilled water and steam and hot water are distributedto other locations. For example, on a school campus the chiller andboiler may be located in a power plant building. The chilled water andsteam are distributed to classrooms in separate buildings. A set ofinsulated pipelines is used to convey the chilled water from the chillerto other locations and back to the chiller. Another set of insultedpipelines is used to carry the steam or hot water from the boiler to theother locations and back to the boiler. It is necessary for the pipes tobe insulated in order to retain the internal temperature of the mediumbeing transported and keep heating and cooling losses at a minimum. Theinsulated pipelines are usually located underground.

So called “pre-insulated piping systems” of the type under considerationare conventional and commercially available. There are predominately twotypes of such pre-insulated piping systems in use: Class-A drainabledryable testable (DDT); and polyurethane or polyisocyanurate “fullybonded” foam systems. In the bonded type system, the foam and outerjacket, being bonded, do not move relative to the inner pipe. In theClass-A type system, on the other hand, the insulated inner pipe isdesigned to move independently of the associated outer jacket. In fact,there is an air gap between the inner pipe and outer carrier pipe in theclass-A type system.

The present application is directed toward the bonded foam type system.These systems utilize a steel pipe to convey fluid, i.e., steam and*superheated water, where the fluid is at a different temperature ascompared to the ambient environment. Around the outside of the steelpipe is a layer of insulating foam such as, for example,polyisocyanurate foam. In the case of high temperature piping systems,the insulating foam serves to keep heat loss from the starting locationof the pipeline to the ending location at a minimum. Around the outsideof the foam is a thin jacket of thermoplastic material, such as highdensity polyethylene (HDPE). The plastic jacket protects the foam frommechanical damage and also provides a watertight seal to preventcorrosion of the steel pipe. Although steel is commonly used for theinner pipe which carries the media to be piped, copper, aluminum orother metals as well as fiberglass, PVC, and similar materials may beutilized, as well.

There have been a number of efforts in the prior art to produce“pre-insulated piping” of the above described type in continuous, ratherthan batch or one section of the pipe at a time processes. U.S. Pat. No3,223,571 is an early continuous process. A film folding device isdisclosed which provides a film covering spaced about the pipe intowhich the foam is injected. The pipe is continuously moved through thefoaming apparatus and when it emerges from the apparatus, the foam isstill generally soft or gel like. It is then allowed to set up and cure.

In the '571 process, as with other similar processes, a relativelycomplex molding apparatus is employed to accommodate the expansion andsetting-up of the foam as the pipe is continuously moved through themolding apparatus. Many of these molding devices were designed similarto “corrugators” of the type used to manufacture corrugated plasticpipe. They featured relatively complicated and expensive endlesscomplimentary moving die systems. Such a system is shown in FIG. 6 ofU.S. Pat. No. 3,876,355. FIG. 3 of U.S. Pat. No. 7,824,595 shows anothersuch complicated “corrugator-style” molding apparatus in which a seriesof endless belt mold sections form a semi-cylindrical recess for shapingthe foam insulation as it passes through the apparatus. The molds aregenerally moveable at approximately the same rate as the pipe as itmoves axially downstream through the mold apparatus.

While the above and similar processes may have succeeded in producingpre-insulated piping in continuous fashion, the molding apparatussection of the process was overly complex and expensive to produce.Also, since the apparatus could only produce one size (diameter) ofpre-insulated pipe, it would be necessary to undertake the expense ofmanufacturing a number of different molding devices to accommodate themanufacture of pipe of various diameters.

Thus, there continues to be a need the improvements in the pre-insulatedpiping manufacturing processes, particularly in continuous pipproduction processes.

SUMMARY OF THE INVENTION

The present invention concerns a continuous process for the productionof pre-insulated metal piping systems, such systems often being used incommercial and industrial settings, such as school campuses, hospitalcomplexes and other distributed HVAC settings where hot or cold fluidsare being transported. The system may be carrying steam in anunderground piping system, for example.

It is one object of the present invention to provide a continuousprocess for the production of pre-insulated piping in which thepreviously overly complicated “corrugator” type molding apparatus isreplaced with a much simpler “drum-roller”, to be described in thewritten description which follows.

The particular piping systems under consideration are familiar to thoseskilled in the relevant industries. Such piping systems are made up offirst and second lengths of insulated and jacketed pipe, each having ajoining end to be joined to an end of the other length. Each pipe lengthcomprises an inner metal carrier pipe having an interior surface and anexterior surface. An envelope of foamed insulation surrounds the innermetal carrier pipe exterior surface. An outer protective jackettypically surrounds the envelope of insulation. The joining ends ofadjacent metal carrier pipe lengths are welded together to form fixedjoints, whereby the adjacent pipe lengths provide a continuous length offluid conduit for conveying, for example, high temperature fluids.

In the continuous production method of the invention, a particular typeof molding apparatus is provided for forming an annulus about a pipe tohe insulated into which foaming material can be injected. In a firststep in the process, a synthetic polymeric film is fed to a film folderthat surrounds a portion of the pipe to be insulated with film, formingan annular region between an interior surface of the film and anexterior surface of the pipe to be insulated. Each section of pipe beinginsulated has a leading end which is fed through the molding apparatusin an axial direction so that the leading end of the pipe pulls the filmin an axial direction as the pipe to be insulated is moved through themolding apparatus and through the annulus.

A foaming material is injected into the annular region between the pipeexterior and the film interior as the pipe moves through the moldingapparatus by injecting the foaming material into an end opening of theannular region. Supports are provided for supporting the pipe as it isfed into the molding apparatus and for supported the insulated pipeemerging from the molding apparatus. The foaming material iscontinuously molded to a substantially uniform radial thickness. Thefoaming material is cured to form a foam insulated pipe.

The special molding apparatus used in the process of the invention is aspecially designed roller-drum having a metal roller-drum body. Themetal roller-drum body has a cylindrical length, an interior surface, anexterior surface, and a plurality of individual rollers arranged in aseries of linearly staggered, circular roller arrays. Each of theindividual rollers is retained in, and free to rotate in, a windowopening provided in the cylindrical length of the roller-drum body.

The linearly staggered, circular arrays of rollers comprise a series oflinearly aligned rollers which make up longitudinal columns when theroller-drum is cut in half and viewed in planar fashion, there alsobeing intermediate rows of rollers running in radial relationship to thecolumns which form offset rows of rollers in the linearly staggered,circular roller arrays. The offset rows and columns of rollers in thelinearly staggered roller array provide approximate 100% coverage of thefoam covered film as the pipe passes through the molding apparatus,providing an annular expansion area about the pipe for the foamingmaterial.

The foaming material which is utilized will typically be a curable foaminsulation selected from the group consisting of polyurethane foams andpolyisocyanurate foam. The use of these type foaming materials isconventional in the industry. The process may further include the stepof extruding a polyolefin coating around at least a portion of the pipewith the insulation thereon to thereby form an outer protective jacketfor the insulated pipe. The lengths of insulated piping being joined maybe part of a pipeline conveying steam, hot water or other hot or coldfluids.

Additional objects, features and advantages will be apparent in thewritten description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified representation of a prior art process for thecontinuous production of pre-insulated piping of the type underconsideration.

FIG. 2 is a simplified view, similar to FIG. 1, of the improvedcontinuous process of the invention.

FIG. 3 is an isolated plan view of one half of the special roller-drumwhich is used in the improved continuous process of FIG. 2, the drumbeing cut in half for ease of illustration,

FIG. 4 is an end view of the roller-drum of FIG. 3.

FIG. 5 is an isolated perspective view of the half portion of theroller-drum of FIG. 3,

FIG. 6 is a partial perspective view of the apparatus used in practicingthe method of the invention showing the end region of a section ofpre-insulated piping exiting the roller-drum molding apparatus.

DETAILED DESCRIPTION OF THE INVENTION

The preferred version of the invention presented in the followingwritten description and the various features and advantageous detailsthereof are explained more fully with reference to the non-limitingexamples included in the accompanying drawings and as detailed in thedescription which follows. Descriptions of well-known components andprocesses and manufacturing techniques are omitted so as to notunnecessarily obscure the principle features of the invention asdescribed herein. The examples used in the description which follows areintended merely to facilitate an understanding of ways in which theinvention may be practiced and to further enable those skilled in theart to practice the invention. Accordingly, the examples should not beconstrued as limiting the scope of the claimed invention.

As has been briefly described, the particular type of piping systemunder consideration includes lengths of insulated and jacketedpre-insulated piping and, more specifically to a bonded foampre-insulated piping system; i.e., the piping is made up of an innercarrier pipe having an interior surface and an exterior surface with anenvelope of foamed insulation surrounding the inner pipe exteriorsurface. The envelope of foamed insulation can be, for example, aninsulating material selected from the group consisting of polyurethanefoams and high temperature polyisocyanurate foams. An outer protectivejacket surrounds the envelope of insulation. The outer jacket canconveniently be formed from high density polyethylene. Each length ofpiping has a joining end for joining to an adjacent length of piping,whereby the adjacent lengths of piping provide a continuous length offluid conduit for conveying high temperature fluids. The section ofpiping, as previously described, is installed in a piping system made upof other sections of piping.

One example of a commercially available pre-insulated piping system ofthe above type is the “HT-406”™ High Temp Steel Piping System sold byThermacor Process, Inc., 1670 Hicks Field Road East, Fort Worth, Tex.76179. The following references, among others, teach the manufacture ofsuch prior art systems: U.S. Pat. Nos. 3,793,4111; 4,084,842; and4,221,405, all to Stonitsch et al.; as well as U.S. Pat. Nos. 6,547,908;5,736,715; 7,037,557; 7,418,979; and 9,377,150, all assigned toThermacor Process, Inc., the assignee of the present invention.

Any reference in this discussion to “sections” or “lengths” of pipe isintended to refer to standard available factory pre-insulated piping ofthe type previously described having an inner metal pipe surrounded byan envelope of foamed insulation, which in turn, is contained within apolyolefin jacket. As referred to briefly above, typical commercialpractice involves the use of steel, copper, aluminum or alloy metalmaterial for the inner carrier pipes. The typical pipe diameters willbe, for example, 4 inches to 12 inches. For high temperature systems,the surrounding envelope of foam insulation is typically formed ofclosed cell polyisocyanurate. The outer protective jacket can be formedof a suitable polyolefin, such as polypropylene, polybutylene,polyethylene, polyvinylchloride and similar protective jackets.

The term “high temperature”, as used in this discussion, means that thepipelines are conveying fluids at temperatures above ambient, typicallyat temperatures of 212° F. and above. In some cases, temperatures of350°-400° F. and higher will be encountered. The expected operatingtemperature of the pipeline will determine the type of outer foaminsulation utilized. For example, 251° F. is generally accepted as thepresent temperature limitation at which polyurethane foam is used inbonded foam systems. Temperatures above about 250° F. generally requirethe use of higher temperature foams, such as the previously mentionedpolyisocyanurate foam. The piping systems of the type illustrated in thedrawings and described in the discussion which follows are typicallyutilized to convey fluids at high temperature and/or pressures. Forexample, a typical steam line might be conveying fluid at, for example,250-350° F.

The above referenced U.S. Pat. No. 7,037,557, assigned to ThermacorProcess, Inc., describes one prior art “batch” manufacturing process inwhich the inner metal carrier pipe is surrounded by an outerthermoplastic jacket which is positioned by means of standoff's. Awaterstop is placed at one end. The foam insulating material from asuitable supply source is then pumped into the annular space between thepipe exterior and the interior of the thermoplastic jacket and allowedto expand and set. A second waterstop is then installed at the oppositeend of the section of pipe. The thickness of foam in the annulus willtypically be at least about 2.5 inches.

While the “batch” process is certainly capable of producing acceptableproduct, it is obviously limited in terms of throughput per hour. Oneuse of the pre-insulated piping systems of the invention is in pipelinesused in the delivery of petroleum and petroleum products over longdistances, e.g., 100-200 mile distances, or further. The batch processesare generally too slow and time consuming and require too much handlingof the pipe being processed to be efficient in such situations. There isobviously a need to provide a continuous process for producing suchpre-piping in order to supply a greater length of piping in a shorteramount of time.

In addition to the above-described “batch” process, prior art“continuous” processes are also known. For example, the followingpatents show such continuous processes: U.S. Pat. Pub. 2015/0375433;U.S. Pat. Pub. 2011/0308659; U.S. Pat. Nos. 3,041,700; 3,876,355;7,824,595; and WO 2011/103606. The typical prior art continuous processis presented in simplified, schematic fashion in FIG. 1 of the Drawings.In FIG. 1, an inner metal carrier pipe 11 is pulled through a moldingapparatus 13, as by a conveyor system (shown schematically as 12 inFIG. 1) located to the right of the main process section. The pipe 11was also supported on the left side as it entered the molding apparatus.The molding apparatus was typically a traveling mold in which moldforming members travel about and along the pipe at substantially therate of movement of the pipe. A synthetic plastic film was typicallydispensed, as from roll 15, and fed to a film folder where it created anannular region about the exterior of the inner carrier pipe. Foam wasdispensed from dispensing head 17 into an end opening of the liner asthe pipe was pulled through the mold section.

As the pipe emerged from the molding apparatus, moving at a reasonablespeed, the foam was generally in a soft or gel state prior to setting.The pipe with its foam coating was typically passed to an extruderstation which extruded a synthetic outer jacket about the foam layer.The synthetic outer jacket was cured in a curing station 21.

One problem with the prior art continuous processes was the fact thatthe molding stations 13 tended to be overly complex and expensive. Theytypically operated in much the same way that “corrugators” for producingplastic corrugated pipe work. A series of die blocks are mounted onendless chains on either side of the inner carrier pipe and travel aboutand along the pipe at substantially the same speed of the pipe, creatingthe annular region into which the foam is injected. The complexity ofsuch systems can be appreciated by reference to FIG. 6 of the abovereferenced U.S. Pat. No. 3,876,355, and to FIG. 3 of the previouslyreferenced U.S. Pat, No. 7,824,595. In addition to the complex nature ofthe “corrugator” sections, a different size mold section was requiredfor each size pipe being insulated.

FIG. 2 shows the improved continuous process for producing pre-insulatedpiping of the invention. In the process of the invention, a specialmolding apparatus 23 (to be further described) is provided for formingan annulus about an inner metal carrier pipe 25 to be insulated intowhich foam can be injected. A synthetic polymeric film 27 is fed from aroll 29 to a film folder (generally at 31) that surrounds a portion ofthe pipe to be insulated with film, forming an annular region between aninterior surface of the film and an exterior surface of the pipe. Thefilm folder is shown in somewhat schematic fashion in FIG. 2, since suchdevices are well known in the relevant industries. The film couldconveniently be, for example, a polyolefin, such as a commerciallyavailable thin polyethylene film, generally less than about 10 mils inthickness.

One such film folder is shown in U.S. Pat. No. 3,223,571, issued Dec.14, 1965, to Straughan, the disclosure of which is hereby incorporatedby reference in its' entirely. Quoting from the description of the '571patent, the film folder described therein consists of a combination of asmooth curve, wing-shaped shoulder portions and a rearward tubularportion. A longitudinal circular opening was provided in the curvedsurface for the axial passage of the pipe being insulated. Extendingrearwardly of shoulder portion is a flexible tubular member, overlappingsplit longitudinally to cause the final overlapping fold of the filmabout the pipe. As the film ribbon is drawn over the smooth curvedshoulder portion, it is automatically shaped into a continuous tubularwrap about the pipe. The film ribbon is of sufficient width that itsedges overlap when it is so folded about the pipe. A film sealing meansis located behind the film folder to seal or interconnect the overlap ofthe film edges. This type folding operation is sometimes referred to asa “cigarette paper” type of folding operation.

In the next step in the method of the invention, the pipe 25 has aleading end (33 in FIG. 2) which is fed through the molding apparatus 23in an axial direction (from left to right in FIG. 2) so that the leadingend of the pipe pulls the film 27 in an axial direction as the pipe tobe insulated is moved through the molding apparatus and through theannulus. At the same time, a suitable foaming material is injected intothe annular region between the pipe exterior and the film interior asthe pipe moves through the molding apparatus 23 by injecting the foamingmaterial from an injector gun 35 into an end opening of the annularregion formed by the film 27. It may be necessary to utilize more thanone injector gun, for example, one gun above the pipe and one gun belowthe pipe for evenly injecting foaming material as the pipe moves throughthe molding apparatus.

While the pipe is moving through the molding apparatus 23, it is beingsupported at either end, as by a conventional roller table on the leftend (not shown), and a conventional conveyor system (shown schematicallyas 37 in FIG. 2) on the right end. The foam material is continuouslymolded in the molding apparatus to a substantially uniform radialthickness and is cured to form a foam insulated pipe. The insulated pipemay have an outer protective jacket applied as at an extrusion station39. The jacked might be, for example, high density polyethylene.

The previously described method steps and apparatus are all similar tothose used in various of the prior art continuous processes discussedabove with one exception. Instead of a “corrugator” type moldingstation, the process of the invention employs a special moldingapparatus which is referred to herein as a “roller-drum” apparatus (23in FIG. 2). As will be apparent from FIGS. 2 and 6, the roller-drumapparatus comprises a roller-drum having a metal roller-drum body 41.The metal roller-drum body 41 has a cylindrical length (“I” in FIG. 6),an exterior surface 42 and an interior surface 44, and a plurality ofindividual rollers 43 arranged in a series of linearly staggered,circular roller arrays. As shown in FIG. 2, more than one roller-drummay be used in the process, depending upon such factors as the diameterof the pipe being insulated, etc.

The individual rollers 43 are shown in greater detail in FIGS. 3-5. Asshown in FIGS. 3 and 5, the plurality of individual rollers 43 are eachretained in and are free to rotate in a window opening provided in thecylindrical length of the roller-drum body. The window openingscommunicate between the interior and exterior surfaces 42, 44 of theroller-drum body 41. By “circular roller array” is meant the patternshown in FIG. 4 of the Drawings (the roller drum being cut in half forease of illustration. The “linearly staggered, circular arrays ofrollers” comprise a series of linearly aligned rollers 43 which make uplongitudinal columns (such as columns 45, 47 and 49 in FIG. 5) when theroller-drum is cut in half for ease of illustration. As also shown inFIG. 5, intermediate rows of rollers (such as the roller array shown inFIG. 4) run in radial relationship to the columns 45, 47 and 49 whichform offset rows of rollers in the linearly staggered, circular rollerarrays. In other words, if the column of rollers beginning with roller57 in FIG. 3 has a center which is one inch from the outer edge 59 ofthe cylindrical roller-drum body 41, then the center of the column offrollers beginning with roller 61 would be located approximately 2 inchesfrom the outer edge 59.

The arrangement of the offset rows 51, 53, 55, and columns 45, 47, 49,of rollers 43 in the linearly staggered roller array provide approximate100% coverage of the film and expanding foam as the pipe passes throughthe molding apparatus 23. By “approximate 100% coverage” is meant thatthe resulting foam covered pipe should not have the “corrugated” lookwhich would be produced in a corrugated pipe manufacturing process.Rather, the exterior or the cured foam should be a smooth as possible.Generally speaking, the larger the number of rollers and the longer thelength of the molding apparatus, the smoother the exterior surface ofthe resulting foam will be.

An invention has been provided with several advantages. The roller-drummolding apparatus of the process replaces the much more complicated andexpensive “corrugator” type molding stations of the prior art processes.The arrangement of the offset rows in the linearly staggered rollerarray provide nearly complete coverage of the film wrap, and hence theexpanding foaming material while the pipe moves through the moldingapparatus. This is accomplished without the use of the “travelling dieblocks” and endless belts or the prior art devices. The result is a moreeconomical process with fewer potential maintenance problems. Thesimplistic nature of the “roller-drum” insures that the apparatus willbe long lasting and simple to maintain. It can be provided in a range ofsizes for different size pipe at a much lower cost than the prior artsystems.

While the invention has been shown in only one of its forms, it is notthus limited but is susceptible to various change and modificationswithout departing from the spirit thereof.

What is claimed is:
 1. A method for the continuous production ofpre-insulated piping where the piping is made up of first and secondlengths of insulated and jacketed pipe, each having a joining end to bejoined to an end of the other length, each pipe length comprising aninner metal carrier pipe having an interior surface and an exteriorsurface, an envelope of foamed insulation surrounding the inner metalcarrier pipe exterior surface, and an outer protective jacketsurrounding the envelope of insulation, the joining ends of adjacentmetal carrier pipe lengths being welded together to form fixed joints,whereby the adjacent pipe lengths provide a continuous length of fluidconduit for conveying high temperature fluids, the method comprising thesteps of: providing a molding apparatus for forming an annulus about apipe to be insulated into which foam can be injected; providing asupport for supporting pipe being fed into the molding apparatus and forsupporting insulated pipe emerging from the molding apparatus; movingthe pipe to be insulated through the molding apparatus; injecting afoaming material into the annulus as the pipe moves through the moldingapparatus; allowing the foaming material to cure to a substantiallyuniform radial thickness to thereby form a foam insulated pipe; whereinthe molding apparatus which is provided comprises a roller-drum with aroller-drum body and having a cylindrical length, the roller drum bodyhaving a plurality of individual rollers set in window openings in thecylindrical length of the roller-drum body, the plurality of rollersbeing arranged in a series of linearly staggered circular arrays;wherein the plurality of individual rollers are each retained in and arefree to rotate in a window opening provided in the cylindrical length ofthe roller-drum body which communicates the interior and exteriorsurfaces thereof, each roller having a central roller axis located at anapproximate mid-region of its respective window opening; and wherein thelinearly staggered circular arrays of rollers comprise a series oflinearly aligned rollers which make up longitudinal columns when theroller-drum is cut in half and viewed in planar fashion, there alsobeing intermediate rows of rollers running in radial relationship to thecolumns which form offset rows of rollers in the linearly staggeredcircular roller arrays, wherein the roller drum is provided with thirtyor more of the linearly staggered, circular arrays of rollers set in thewindow openings in the cylindrical length of the roller drum body.
 2. Amethod for the continuous production of pre-insulated piping where thepiping is made up of first and second lengths of insulated and jacketedpipe, each having a joining end to be joined to an end of the otherlength, each pipe length comprising an inner metal carrier pipe havingan interior surface and an exterior surface, an envelope of foamedinsulation surrounding the inner metal carrier pipe exterior surface,and an outer protective jacket surrounding the envelope of insulation,the joining ends of adjacent metal carrier pipe lengths being weldedtogether to form fixed joints, whereby the adjacent pipe lengths providea continuous length of fluid conduit for conveying high temperaturefluids, the method comprising the steps of: providing a moldingapparatus for forming an annulus about a pipe to be insulated into whichfoam can be injected; providing a support for supporting pipe being fedinto the molding apparatus and for supporting insulated pipe emergingfrom the molding apparatus; feeding a synthetic polymeric film to a filmfolder that surrounds a portion of the pipe to be insulated with film,the film forming an annular region between an interior surface of thefilm and an exterior surface of the pipe; wherein the pipe has a leadingend which is fed through the molding apparatus in an axial direction sothat the leading end of the pipe pulls the film in an axial direction asthe pipe to be insulated is moved through the molding apparatus;injecting a foaming material into the annular region between the pipeexterior and the film interior as the pipe moves through the moldingapparatus by injecting the foaming material into an end opening of theannular region; allowing the foaming material to cure to a substantiallyuniform radial thickness to thereby form a foam insulated pipe; whereinthe molding apparatus which is provided comprises a roller-drum with ametal roller-drum body, the metal roller-drum body having a cylindricallength, an exterior surface and an interior surface, the roller drumbody having a plurality of individual rollers set in window openings inthe cylindrical length of the roller-drum body, the plurality of rollersbeing arranged in a series of linearly staggered circular arrays;wherein the plurality of individual rollers are each retained in and arefree to rotate in a window opening provided in the cylindrical length ofthe roller-drum body which communicates the interior and exteriorsurfaces thereof, each roller having a central roller axis located at anapproximate mid-region of its respective window opening; wherein thelinearly staggered circular arrays of rollers comprise a series oflinearly aligned rollers which make up longitudinal columns when theroller-drum is cut in half and viewed in planar fashion, there alsobeing intermediate rows of rollers running in radial relationship to thecolumns which form offset rows of rollers in the linearly staggeredcircular roller arrays; and wherein the offset rows and columns ofrollers in the linearly staggered roller array provide approximate 100%coverage of the film and expanding foam as the pipe passes through themolding apparatus; wherein there are twenty or more of the linearlystaggered, circular arrays of rollers set in the window openings in thecylindrical length of the roller drum body.
 3. The method of claim 2,wherein the foam insulation is selected from the group consisting ofpolyurethane foams and polyisocyanurate foam.
 4. The method of claim 3,further comprising: The step of extruding a polyolefin coating around atleast a portion of the pipe with the insulation thereon to thereby forman outer protective jacket for the insulated pipe.
 5. The method ofclaim 4, wherein the lengths of insulated piping being joined are partof a pipeline conveying steam, hot water or other hot or cold fluids. 6.The method of claim 5, wherein the pipe being insulated is a metalcarrier pipe formed of steel of a given gauge.
 7. The method of claim 6,wherein the outer protective jacket is a high density polyethylenejacket material.